Person who is more retarded than usual. He or she is so retarded that if they go to court they will be pronounced legally retarded.
OMG those girls are legally retarded.
In the state of Maine one is legally retarded upon using LSD several times (i think it is 3 or 4).
Kevin: Hey man, I did LSD 3 times this week. What a trip...
John: I think you may be legally retarded in the state of Maine.
Nick: But your not retarded.
Kevine: Thanks man, thanks, that really means alot to me.